iOS設計模式 - 代理

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iOS設計模式 - 代理

 

原理圖

 

說明

1. 代理模式大家都用過,但用抽象基類NSProxy實現代理估計鮮有人用

2. 本人用NSProxy實現了代理模式,對於理解訊息轉寄機制有點協助

 

源碼

https://github.com/YouXianMing/ProxyPattern

////  AbstractProxy.h//  AppProxy////  Created by YouXianMing on 15/8/4.//  Copyright (c) 2015年 YouXianMing. All rights reserved.//#import <Foundation/Foundation.h>@interface AbstractProxy : NSProxy/** *  被代理對象 */@property (nonatomic, weak) id  customer;/** *  代理客戶 * *  @param customer 實現了某種協議的客戶 * *  @return 代理對象 */- (instancetype)initWithCustomer:(id)customer;@end

////  AbstractProxy.m//  AppProxy////  Created by YouXianMing on 15/8/4.//  Copyright (c) 2015年 YouXianMing. All rights reserved.//#import <objc/runtime.h>#import "AbstractProxy.h"#import "AbstractExcute.h"@implementation AbstractProxy- (instancetype)initWithCustomer:(id)customer {    self.customer = customer;    return self;}#pragma mark - NSProxy- (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector {        if ([self.customer respondsToSelector:aSelector]) {                return [self.customer methodSignatureForSelector:aSelector];            } else {                AbstractExcute *excute = [AbstractExcute shareInstance];        return [excute methodSignatureForSelector:NSSelectorFromString(@"nullExcute:")];    }}- (void)forwardInvocation:(NSInvocation *)invocation {        SEL selector = [invocation selector];    if ([self.customer respondsToSelector:selector]) {                [invocation setTarget:self.customer];        [invocation invoke];            } else {            NSString *selectorString = NSStringFromSelector(invocation.selector);                invocation.selector    = NSSelectorFromString(@"nullExcute:");        AbstractExcute *excute = [AbstractExcute shareInstance];        [invocation setTarget:excute];                const char *className      = class_getName([self class]);        NSArray    *classNameArray = nil;        if (self.customer) {                        classNameArray = @[[NSString stringWithUTF8String:className], selectorString, @""];                    } else {                    classNameArray = @[[NSString stringWithUTF8String:className], selectorString];        }                [invocation setArgument:&classNameArray atIndex:2];        [invocation invoke];    }}@end

////  AbstractExcute.h//  AppProxy////  Created by YouXianMing on 15/8/4.//  Copyright (c) 2015年 YouXianMing. All rights reserved.//#import <Foundation/Foundation.h>@interface AbstractExcute : NSObject+ (instancetype)shareInstance;@end

////  AbstractExcute.m//  AppProxy////  Created by YouXianMing on 15/8/4.//  Copyright (c) 2015年 YouXianMing. All rights reserved.//#import "AbstractExcute.h"@implementation AbstractExcute+ (instancetype)shareInstance {    static AbstractExcute *sharedAbstractExcute = nil;        static dispatch_once_t predicate;    dispatch_once(&predicate, ^{        sharedAbstractExcute = [[self alloc] init];    });        return sharedAbstractExcute;}- (void)nullExcute:(NSArray *)className {    if (className.count == 3) {                NSLog(@"%@ 設定了代理,但該代理沒有實現 %@ 方法", className[0], className[1]);            } else {            NSLog(@"%@ 沒有設定代理,方法 %@ 沒有執行", className[0], className[1]);    }    }@end

 

細節

NSProxy子類實現的關鍵所在

 

iOS設計模式 - 代理